Prosecutors are intensifying their probe into alleged corruption at South Korea's sole aircraft manufacturer, as they raided its headquarters once again Wednesday to obtain evidence for suspected price manipulation.

The Seoul Central District Prosecutors' Office sent investigators to the headquarters of the Korea Aerospace Industries Co. in Sacheon, 437 km south of Seoul, and its offices in the capital earlier in the day, it said.

They mainly searched KAI's development division this time, based on the evidence obtained so far that revealed its possible involvement in the malpractice.

This is a second time that prosecutors have raided both KAI's main and Seoul offices, after it carried one out two weeks ago. The prosecutors already conducted two separate raids on KAI headquarters and its subcontractors on July 14 and 18.

The defense company is accused of inflating expenses for the development of a utility helicopter known as the Surion and pocketing unfair profits worth some 24 billion won ($21.4 million).

The prosecution also suspects that key KAI officials offered business favors to subcontractors that took part in the price manipulation, while also taking bribes from them.

KAI has been involved in high-profile defense projects to develop the Surion utility helicopter, T-50 supersonic trainer jet and FA-50 light attack fighter.

From the two previous searches, prosecutors have secured evidence that possibly implicates KAI officials in inflating the cost price of equipment for the development projects. 

On Monday, prosecutors put a KAI official suspected of being a key man in the case on their wanted list and released his face photo to the public. (Yonhap)